Color photography or cinematography



Patented June 20, 1939 I v 2,163,325 UNITED STAT signor to Truecolour Film Limited, London, England, a British company I No Drawing. Application October 28, 1937, Se-

rial No. 171,593. In Great Britain October 29,

The present invention relates to the production of colored records on photographic material of the type comprising a plurality of superposed silver halide emulsion layers differentially sensithe desired gradation values for the different Claims. (01. 95- 2) colored images. If the color development were permitted to proceed to gamma infinity, a considerable amount of color fog would be formed in those layers in, which the color-development 5' tised for different regions of the spectrum and proceeds rapidly. r 5 each containing color-forming components It has now been found that the difficulties met adapted to react with a diamine or aminophenol with in the direct processing of the latent imdeveloper to produce diiferently colored images ages in such emulsion layers containing colorin the diiferent layers. formers may be overcome by a method which in In the manufacture and processing of such ma,- accordance with the invention, consists in first 0 terial difliculties are encountered owing to the developing the saidlatent images with a develfact that the color-forming components tend to oper which is incapable of affecting the 'colordiffuse or bleed from one layer to the other durformers in such layers, removing the unaffected ing manufacture or during the development of silver halide, converting the developed silver the material. It has been proposed to overcome images into redevelopable silver salt images and 15 this difficulty in such a manner that the colorredeveloping the material in a developer which former or an intermediate product thereof is is capable of reacting with the color-formers in present in the layer in such a state that as dethe layers. velopment proceeds it only comes into solution by It has heretofore been proposed in British patreaction with the by-products of the developer. ent specification No. 447,092 to process a photo-' 20 For example,a color-former of an acid nature may graphic material, embodying several emulsion be insolubilised by conversion into a metal salt, layers which do not contain color-formers, by and a color-former of a basic nature may be first developing the layers to form silver images insolubilised by conversion into a fatty acid salt therein, fixing arid washing the material and or a resin acid salt. then bleaching the silver images to redevelopable 25 On the other hand, it has been proposed to silver salt images, after which the layers are reemploy color-formers of opposite characters in developed with a developer containing a colorthe adjacent layers. Thus, in one layer there forming component in order that all the latent may be a color-former of an acid character, while images in said layers can be color-developed to in the adjacent layer or layers a color-former or one color. Subsequently. the material was in- 30 color-formers of a basic character is/are emsertedin a loaded bleaching bath to bleach some ployed. of said images and redeveloped in another color- Another proposal is contained in British patforming developer to produce a different color in cut specification No. 458,400, which consists in those layers that were bleached, and this pro- 5 employing color-formers containing a chemical cedure was repeated with different color-form- 5 group of a substantive character. ing developers until the' imagesin all the layers The processing of such material may be perhad been processed to different colors. formed by thedirect development of the latent The present invention is restricted to the procimages with a diamine or similar color-forming essing of photographic material in which at least 40 developer, or by the production of reversed imsome of the layers contain color-forming com- 40 ages by first developing the material with a deponents prior to exposure, which components veloper such as metol which is incapable of reare capable of reacting with the oxidation prodacting with the color-formers, removing the deucts of suitable developers to form differently veloped images and redeveloping the remaining colored images in such layers at a single operasilver halide with a color-forming developer to tion. 45 produce reversed color images in the different In carrying the invention into effect a photolayers, graphic material may be employed comprising In the production of reversed images thematethree photographic emulsion layers which may rial can be left in the solution of the color-formeither be disposed all on one side ofv a support .50 ing developer as long as is required for the reason or two may be disposed on one side and a third 5 that no damage can occur to the image in a layer on the other side of the support, and such layers which is already fully developed, while developmay contain suitable color-formers of such a ment in the other layer or layers continues. character in accordance with the prior art that In the processing of such a photographic madiffusion or bleeding from one layer to the other terial to form a record of a negative character by is minimised. The said layers or some of them 55 color-developing the latent images produced on are differently sensitised for different regions of exposure, the dimculty is encountered that dethe spectrum, and if desired between some or all velopment tends to proceed at a different rate in of said layers known decolorisable filter layers the diiferent layers, so that it is difficult to obtain may be provided, and in addition, if desired, at

00 the rear of the material may be provided an antig0 terial comprising a plurality of superposedsilver halation backing which is capable oi removal or Metol Sodium sulphite .do 30 Sodium carbonate do 45 Potassium bromidedo 0.5 Water, q. s c 2,000

The unaflected silver halide in thelayers is then removed in a solution of sodium thiosulphate and the material thoroughly washed. The silver images in the layers are then converted into a silver salt which is capable oi redevelopment with a color-forming developer, in some cases after reexposure to light. A suitable silver-salt for this purpose is silver i'errocyanide in which case the following bleach bath could be employed:-

Potassium ierricyanide gm 20 Ammonia 28% solution ....cc 20 Water. 'q. s. do -100 The material may be re-exposed to light, although this step is not normallyneceasary. and inserted in a developer, the oxidation products of which are adapted to react with the color-formers in the layers at the points where development 01 the'silver salt occurs, to produce colored images in tho' 'diiierent layers; such color-forming developers are well known in the art but the following diethylparaphenylenediamine is quoted by way of example 'only:- Diethylparaphenylenediamine hydrochloride gm 0.82 Sodium sulphite (crystals) ..do.. 5 Potassium carbonate (anhydrous) do 20 Water, q. s cc 1,000

01' course, the photographic material may comprise .more than three photographic emulsion layers and all or only some 01' said layers may contain color-formers. Thus, a material suitable for a four-color process in which a fourth emulsion layer is provided intended to give a black and white image, may comprise three layers containing suitable color-formers while the fourth layer may be an ordinary photographic emulsion. Moreover, whether the material comprises three or four emulsion layers some of the layers in which colored images are produced may be processed by other methods than those described herein.

Thus again, a photographic material comprising two emulsion layers on one side of the support and a single layer on the other side of the support may contain different color-formers in the said two layers, while the layer on the other side-of the support may be an ordinary photographic emulsion, a color image being formed therein during the processing by other knownprocesses of color development'wherein the colorformer is mixed with the developer, by dyetoning, chemicaltoning or otherwise.

I claim: e

1. A method of processing a photographic mahalide emulsion layers containing color-forming components 'to produce diiierently colored images in the diiierent layers comprising developing the latent image in all of said layers with a developer incapable of aiiecting the said colorformers, removing the unaiiected silver halide from said layfli's, converting the developed silver images into silver salt images which are capable oi redevelopment and developing said silver salt images with a developer, the oxidation products oi which arecapable of reacting with the said color-formers to produce diil'erently colored images in the layers. t

2. A method oi producing a non-reversed color record on a photographic material comprising superposed silver halide emulsion layers sensitive to diflerent spectral regions and containing colori'orming components to partake in the production oi the colored images in said layers which consists in developing the latent images in said emulsion layers to silver with a developer which does not affect the color-formers, removing the unaflected silver halide iromsaid layers, converting the developed silver images into developwhich consists in developing silver images in all of said layers with a developer which doesnot ail'ect the color-forming components, removing the unaffected silver halide from said layers, converting the developed silverimages into redevelopable silver salt images and redeveloping the material in a paraphenylenediamine developer to produce diil'erently colored images in all oi said layers.

4. A method of producing a non-reversed mulmaterial comprising a plurality of superposed silver halide emulsion layers containing colorforming components which consists in developing silver images in all of said layers, removing unaffected silver halide in said layers, converting said silver images into developable silver salt images, developing the latter images in a developer capable of reacting with said color-forming components to produce diii'erently colored images in said layers and finally removing developed silver from said layers.

5. A method of producing a non-reversed multi-color photographic record on photographic material comprising a plurality of superposed silver halide emulsion layers containing colorformlng components which consists in developing silver images in all of said layers, removing the unafi'ected silver halide from said layers, converting the developed silver images into silver ferro-cyanideand developing the latter images with a developer capable of reacting with the color-forming components to produce differently colored images in said layers.

' EDGAR SANDERS- DOIGORUKI. 

